1. Field of the Invention
This invention is directed to flexible lighting strips for rope lighting, cove lighting, and signage applications.
2. Description of the Prior Art
Flexible lighting strips, also called rope lights, are used for lighting both interior and exterior structures and can be used for sign applications. Existing lighting strips do not allow a combination of flexibility and rigidity desired by users to configure rope lights into any selected configuration with ease. Color chasing and color mixing capabilities are limited.
Prior art in the sign industry includes the utilization of neon lamps, fluorescent lamps, and incandescent lamps. The drawbacks for neon and fluorescent lamps include difficulty in starting in cold temperatures, dangerous high-voltage operation, and the presence of mercury that in turn creates an environmental hazard. Incandescent lamps generate a large amount of heat, have poor resistance to vibration, have short lamp life, and consume large amounts of energy with the result that most of their light energy is wasted as infrared heat energy.
Light emitting diode (LED) technology makes possible the replacement of short lamp life with longer lamp life and energy deficient light sources using energy efficient light sources that are long lived and cooler running. Color output LEDs can emit red (R), green (G), blue (B), and yellow (Y) light, or white light. Brighter color mixing with better color rendering than in prior art technology is a result. Color additive mixing of LEDs can produce the secondary colors cyan (C), yellow (Y), magenta (M) and white light. Mixing green and blue gives cyan. Mixing green and red gives yellow. Mixing red and blue gives magenta. Mixing RGB plus a separate Y generates a truer white light with better color rendering than just combining RGB.
It is noted that color gel filters are not necessary with RGBY color mixing light technology, which in itself generates the full light spectrum. Color efficiency in LEDs is much better than incandescent filament lamps, which require a specific color gel or filter. This can waste up to about 90 percent of the light energy of incandescent lamps. LEDs on the other hand deliver 100 percent of their energy as light and further emit a more intense selected colored light. This energy efficiency of LEDs extends to the emitting of white light as well. There are two ways of using LEDs to produce white light in this invention: 1) using LEDs that produce white light exclusively, or 2) using LEDs to emit RGBY at the same time and at equal output intensities.
Besides generating less heat, LEDs are more energy efficient, more durable, and last longer than conventional light sources. The solid state design of LEDs makes them durable and robust and gives them the capability of withstanding shock, vibration, frequent power cycling and operation in extreme cold and hot temperatures. LEDs have an average usable life of typically 100,000 hours or more when operated within design specifications. LEDs are mercury free. LED technology now includes multi-chip and multi-light LED arrays, so that LEDs are available in a wide range of colors in unique combinations. Clearly for many applications LEDs now compete directly with incandescent filament, neon, and fluorescent light sources.
In the preferred embodiment of the present invention, light emitting diodes in different colors can be mounted onto a flexible circuit board that is twisted into a helix and inserted into a flexible tubular housing. This unique combination of a flexible circuit board and a flexible tubular housing will allow for a more versatile and improved flexible shape retaining rope light and cove light. In addition, the ease of manufacturability and full 360-degree omni-directional and uniform light dispersion is very important.
In an alternate embodiment of the present invention, light emitting diodes in white and different colors are mounted onto a flat long flexible circuit board with multiple repeating cutouts preferably diamond shaped that extend through the circuit board substrate. The circuit board is then rolled into a cylinder with the LEDs mounted to the interior of the circuit board and pointing inwards into the cylinder or alternatively, the LEDs are mounted to the exterior of the circuit board and pointing outwards from the cylinder, or both. The entire cylindrical assembly is inserted into a flexible outer tubular housing. A stiffening member contained in the outer tubular housing and optionally on the flexible circuit board itself will allow the complete LED lighting strip to be flexible because of the diamond shaped cutouts provided on the flexible circuit board, and will allow for some rigidity and memory for proper installation and assembly of the complete flexible LED lighting strip. This unique combination of a flexible circuit board and a flexible tubular housing will allow for a more versatile and improved flexible shape retaining rope light, cove light, and signage light. In addition, this invention has ease of manufacturability and full 360-degree omni-directional and uniform light dispersion that is very important. Previous inventions have been developed to try and accomplish this task, but have not been successful.
Color Kinetic's iColor Accent, Cove, and Fresco line of LED fixtures are available only in rigid linear transparent or translucent housings that offer no flexibility or versatility at all. To achieve a circular arrangement, for example, multiple linear fixtures have to be aligned edge to edge to approximate the curved outline. The iColor Accent, Cove, and Fresco fixtures also use rigid circuit boards with the LEDs mounted perpendicular to the circuit boards, therefore the light dispersion output from the LEDs are generally in the forward direction offering only at most approximately 180 degrees of coverage.
Gelcore Lighting offers their Tetra LED System and Lumileds Lighting offers their Chip Strip Contour Lighting System for signage applications. Both systems consist of a series of individual LED modules mounted onto rigid circuit board disks. Each LED module that is mounted onto a rigid circuit board disk is attached by power leads to an adjacent similarly configured LED module and rigid circuit board disk, and so on. Although the power leads offer flexibility as far as configuring the location of the LED modules themselves, there is no overall protective housing for all the modules. Also, since the LEDs are mounted onto rigid circuit boards, again the light dispersion output from the LEDs are generally in the forward direction also offering only approximately no more than 180 degrees of coverage.
In U.S. Pat. No. 6,394,623 issued to Tsui May 28, 2002, a translucent flexible rope light is disclosed and methods of forming and using the same. The invention uses exposed main conductors consisting of multi-strand wire connected to a plurality of spaced-apart lights, both extending substantially in parallel for substantially the entire length of the rope light. A flexible sheath having a continuous annular shape encases the conductors and plurality of lights. Although this invention uses a flexible tubular housing, the plurality of lights are disclosed as discrete lights wired directly together in series with the main conductors and plurality of lights positioned in a physical parallel orientation with each other throughout the length of the rope light. This invention does not employ a flexible circuit board and the configuration will not allow for a full dispersion of light output from the plurality of lights as required.
In U.S. Pat. No. 6,394,626 issued to McColloch in May 28, 2002, a flexible light track for signage is disclosed consisting of a plurality of modules separately and mechanically connected to a flexible frame to which light emitting diodes and positive and negative leads are mounted to each module. The modules are designed to be mounted flat onto the flexible frame. As this invention was designed for signage use only, an integral flexible tubular housing is not included. As before, this configuration will not allow for a full dispersion of light output from each light emitting diode mounted to each module.
Lastly, in U.S. Pat. No. 6,406,166 issued to Ko Jun. 18, 2002, a chasing rope light using a flexible core tube with at least two separate series string of light emitting diodes each individually connected to a diode rectifier. This rope light was designed to operate on an alternating power source such that only one series string of light emitting diodes will turn on at a time, thereby creating the chasing effect. Although this invention calls for a flexible core tube housing, it also does not employ a flexible circuit board. The major disadvantage here being not all the light emitting diodes in the separate series strings can be turned on at the same time. This invention functions only as a chasing rope light.
A light emitting diode light apparatus in accordance with the present invention that is a substantial improvement over the prior art mentioned above will be appreciated by those skilled in the art from the following summary and detailed description of the invention.